1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
2. Description of the Related Art
The oscillation wavelengths of semiconductor lasers that are currently being employed as image exposing units are relatively long and between 650 nm and 820 nm, and hence efforts are being made to develop electrophotographic photosensitive members that are highly sensitive to light of such long wavelengths. Furthermore, in terms of high resolution, efforts are also being made to develop electrophotographic photosensitive members that are highly sensitive to light of semiconductor lasers whose oscillation wavelengths are short.
Azo pigments and phthalocyanine pigments are known as charge generation substances representing a high degree of sensitivity relative to light of such a long wavelength region and also to light of a short wavelength region.
Thus, an electrophotographic photosensitive member formed by using an azo pigment or a phthalocyanine pigment has excellent sensitivity characteristics. On the other hand, however, the photo carriers generated by such an electrophotographic photosensitive member are apt to remain in a photosensitive layer and give rise to a problem of generating potential fluctuations such as a ghost phenomenon because the member operates as a type of memory.
Japanese Patent Applications Laid-Open Nos. H02-298951, H06-273953 and H05-142813 disclose the use of a benzophenone compound for electrophotographic photosensitive members. The advantages of using a benzophenone compound include suppression of degradation of a charge transport substance by ultraviolet rays (Japanese Patent Application Laid-Open No. H02-298951), prevention of photooxidation of a charge generation substance and suppression of a rise of residual potential (Japanese Patent Application Laid-Open No. H06-273953), and sensitization of pyrrolopyrrole compounds (Japanese Patent Application Laid-Open No. H05-142813).
However, none of these patent applications discloses a benzophenone compound having one or more amino groups as substituent.
Japanese Patent Application Laid-Open No. S52-23351 discloses an electrophotographic photosensitive member containing a polymeric compound having a carbazole ring as side chain and a basic compound as principal ingredients, as an example of using a benzophenone compound having one or more amino groups as substituent. The object of the cited invention is to improve the low charge transport ability and provide the electrophotographic photosensitive member with plasticity for improving the poor film forming performance, which are a drawback of polyvinyl carbazole.
Thus, various attempts have been made to date to obtain improved electrophotographic photosensitive members.
However, there has been in recent years and still is a strong demand for improving the problem of degradation of image quality due to a ghost phenomenon that can occur under various environments from the viewpoint of achieving a higher image quality.